The need to provide a resonate cavity of stable optical length for certain laser applications is well known. For example, stable resonator configurations have been used to enhance single frequency operation and mode-locking. In this context, a stable resonator is intended to mean that the length of the resonant cavity (measured along the laser beam between the end mirrors) is held constant.
A number of approaches have been taken in the prior art to improve the stability of the resonator. For example, it is well known that the stability of the cavity can be improved if all optical components are mounted on a bar having a relatively low thermal coefficient of expansion. One suitable material is Invar. In use, the bar is connected to the frame or laser housing through some form of kinematic mounting. A good kinematic mounting will minimize the number of contact points with the bar while removing any degrees of freedom of motion of the bar with respect to the frame. In this manner, any force placed on the frame, which could misalign the optical elements, will not be transferred to he bar. In accordance with one aspect of the subject invention, an improved kinematic mounting for an Invar bar is disclosed.
Although materials such as Invar have a relatively low coefficient of thermal expansion, the length of the Invar bar will change to some degree in response to variations in temperature. Various electromechanical servo mechanisms have been developed to compensate for gross deviations in length due to temperature. Another aspect of the subject invention is to provide a new and improved means for automatically compensating for small variations in the change in length of a support bar such that the total length of the resonant cavity can be maintained constant despite small environmental temperature changes.
The mirrors at the end of a resonant cavity are typically mounted in an adjustable support. A standard support consists of two plates which can be rotated with respect to each other about two pivot lines. The adjustments comprise a pair of screws for making this adjustment. The problem with this standard mirror mount is that as the mirror is rotated, the mirror face moves with respect to the beam path, changing the length of the resonant cavity. In the final aspect of the subject invention, an improved gimbal mirror mount is disclosed which overcomes this difficulty.
Accordingly, it is an object of the subject invention to provide a new and improved laser having enhanced stability.
It is another object of the subject invention to provide an improved kinematic mounting assembly for a laser.
It is still another object of the subject invention provide a new and improved kinematic mounting assembly for connecting a mirror support structure or bar to a frame of a laser.
It is still a further object of the subject invention to provide improved mirror mounting assemblies.
It is still another object of the subject invention to provide improved mirror mounting assemblies which are designed to maintain the length of the resonant cavity in the laser.
It is another object of the subject invention to provide a gimbal assembly for pivotally mounting a laser mirror.
It is still a further object of the subject invention to provide a mounting assembly for a mirror which automatically compensates for changes in the length of a support bar due to temperature.